The UK's most complete GLP-1 guide
Every Question Answered. Every Side Effect Explained.
- How GLP-1 medications work
- Mounjaro vs Wegovy compared
- Injection instructions
- Side effects & solutions
- What to eat on treatment
- FAQs answered
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How to Order Mounjaro Online in the UK
Ordering Mounjaro online in the UK requires a prescription from a licensed UK prescriber following a clinical assessment. You cannot buy Mounjaro without a prescription. Access is available through NHS specialist weight management services or through private online prescribing services. Understanding your eligibility and the difference between NHS and private routes will help you navigate the process. This guide explains how Mounjaro (tirzepatide) works, who qualifies, and how to access it safely in the UK. Use our free GLP-1 weight loss calculator to estimate potential results, and our BMI calculator to check your eligibility status.
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Calculate Your BMI Instantly
Enter your height and weight below. Supports both imperial (stone & lbs) and metric (kg). Results include NHS category, healthy weight range, and ethnicity adjustments.
What Is BMI and Why Does It Matter?
Body Mass Index (BMI) is the most widely used screening tool for assessing whether your weight falls within a healthy range. Used by the NHS, GPs, and weight management services across the UK, BMI provides a quick snapshot of your weight relative to your height. The formula is simple: your weight in kilograms divided by your height in metres squared (kg/m²).
While BMI isn't a perfect measure — it doesn't account for muscle mass, bone density, or fat distribution — it remains the standard first step in identifying potential weight-related health risks including type 2 diabetes, cardiovascular disease, high blood pressure, and certain cancers.
The NHS also recommends adjusted thresholds for people of South Asian, Chinese, or Black African heritage — a BMI of 23 or above is classified as overweight, and 27.5 as obese. Our calculator includes this adjustment as a one-click toggle.
NHS vs Private: Your Options for Mounjaro in the UK
NHS Route: NICE has approved tirzepatide (Mounjaro) for use within NHS specialist tier 3 and tier 4 weight management services. You cannot order Mounjaro directly online through the NHS—you must be referred by your GP to a specialist weight management service in your area. Eligibility requires a BMI of 30 kg/m² or above, or 27–29.9 kg/m² with weight-related health conditions such as type 2 diabetes, high blood pressure, or cardiovascular disease. South Asian, Chinese, Black African, or Black Caribbean adults may qualify at lower BMI thresholds (from BMI 27.5). NHS waiting lists vary by region—some areas have significant delays.
Private Route: Private online prescribing services can issue Mounjaro prescriptions without NHS referral. After an online clinical assessment with a UK-licensed prescriber, a prescription is issued and dispensed by a GPhC-registered pharmacy. This is faster than NHS routes but involves private costs (typically £129–£320+ per month depending on dose). Both routes require a genuine clinical assessment—you cannot simply order without prescription review.
Clinically BackedWeight Loss
No appointments. No waiting rooms. Just care — from a UK-regulated online pharmacy.
How It Works
Three simple steps to understand your weight and take action.
Enter your height and weight in our free calculator. Get your BMI, NHS category, healthy weight range, and ethnicity-adjusted thresholds instantly.
If your BMI suggests you're overweight or obese, explore our GLP-1 calculators to project potential weight loss on Mounjaro or Wegovy.
Use our progress tracker to log your weight weekly, visualise your journey with charts, and stay motivated — all stored privately in your browser.
Free Weight Loss Tools & Guides
Everything you need to understand your weight, explore medication options, and track your progress — completely free.
Mounjaro Eligibility and Dose Titration
Mounjaro eligibility is assessed individually based on BMI, health conditions, and medical history. Starting dose is 2.5 mg once weekly, then titrated upwards every 4 weeks through 5 mg, 7.5 mg, 10 mg, 12.5 mg to a maximum of 15 mg. Clinical trials showed that at 15 mg, tirzepatide helped participants lose an average of 20.9% of body weight over 72 weeks—though individual results vary significantly. You'll need regular check-ins with your prescriber to assess tolerability, side effects, and progress. Common side effects include nausea, diarrhoea, and constipation, which often improve as your body adjusts. Compare Mounjaro vs Wegovy (semaglutide) with your prescriber to understand which GLP-1 medication might suit you best.
- Dual GIP/GLP-1 receptor agonist
- Up to 22.5% body weight loss (SURMOUNT-1)
- Weekly injection, dose escalation over 20+ weeks
- Available via private prescription in the UK
- Doses: 2.5mg → 5mg → 7.5mg → 10mg → 12.5mg → 15mg
- GLP-1 receptor agonist
- Up to 15–17% body weight loss (STEP trials)
- Weekly injection, 5-step dose escalation
- NHS & private prescription available
- Doses: 0.25mg → 0.5mg → 1mg → 1.7mg → 2.4mg
Mounjaro vs Wegovy: Head-to-Head
A side-by-side comparison of the two most popular GLP-1 weight loss medications available in the UK.
| Feature | Mounjaro | Wegovy |
|---|---|---|
| Drug class | Dual GIP/GLP-1 agonist | GLP-1 agonist |
| Active ingredient | Tirzepatide | Semaglutide |
| Avg. weight loss | 15–22.5% | 12–17% |
| Key trial | SURMOUNT-1 (2022) | STEP 1 (2021) |
| Max dose | 15 mg weekly | 2.4 mg weekly |
| Escalation period | 20–32 weeks | 16–20 weeks |
| Administration | Weekly injection (pen) | Weekly injection (pen) |
| NHS availability | Private prescription only | NHS & private |
| Approx. private cost | £150–£250/month | £150–£300/month |
| Common side effects | Nausea, diarrhoea, constipation | Nausea, vomiting, diarrhoea |
Data sourced from SURMOUNT-1 and STEP 1 clinical trials. Costs are approximate and vary by provider. Always consult a prescriber.
Am I Eligible for Weight Loss Medication?
In the UK, eligibility for GLP-1 weight loss medications like Mounjaro and Wegovy is based on your BMI and overall health profile.
- BMI of 30 or above (obese)
- Age 18 or over
- No contraindicated conditions
- Committed to lifestyle changes
- BMI of 27 or above
- Plus type 2 diabetes
- Or high blood pressure
- Or obstructive sleep apnoea
Use our BMI calculator to check whether your BMI falls within the eligible range.
How We Built These Tools
Every calculator and guide on myweightcheck is built with accuracy and transparency in mind. Our BMI calculator uses the standard WHO formula with NHS-aligned category thresholds. Our GLP-1 projections are modelled on published clinical trial data from SURMOUNT and STEP studies.
All data stays on your device. We don't require sign-ups, and we don't store your health information on any server. Your progress tracker saves data locally in your browser using localStorage, so only you can see it.
We're based in the UK and our tools are designed specifically for UK users — supporting stone & lbs by default, referencing NHS guidelines, using NICE-approved medication data, and linking to GPhC-registered pharmacies.
Frequently Asked Questions
Common questions about BMI, weight loss medications, and our free UK tools.
Can I order Mounjaro online without a prescription in the UK?
No. Mounjaro is prescription-only in the UK and cannot be ordered without a valid prescription from a licensed prescriber. Both NHS and private online prescribing services require a clinical assessment before issuing a prescription. Never purchase Mounjaro from unregulated sources.
What's the difference between NHS and private Mounjaro prescribing?
NHS prescriptions come through specialist tier 3/4 weight management services after GP referral, often with waiting lists. Private prescribing is faster—you undergo an online clinical assessment and receive a prescription from a private prescriber, then collect from a pharmacy. Private costs apply; NHS is free but availability varies by region.
Am I eligible for Mounjaro through the NHS?
You may be eligible if you have a BMI of 30 or above, or 27–29.9 with weight-related health conditions (type 2 diabetes, high blood pressure, cardiovascular disease, sleep apnoea). South Asian and Black African/Caribbean adults may qualify at lower thresholds. Your GP will assess your individual circumstances and refer you to specialist services if appropriate.
How long does tirzepatide dose titration take?
Standard dose titration takes 20+ weeks to reach maximum dose (15 mg). You start at 2.5 mg, then increase by one step every 4 weeks as tolerated. Your prescriber may adjust this timeline based on side effects or clinical response. Regular monitoring with your prescriber ensures safe escalation.
What should I expect during an online Mounjaro clinical assessment?
You'll be asked about your weight history, BMI, health conditions (diabetes, blood pressure, heart disease), current medications, allergies, and lifestyle. The prescriber will review your eligibility against MHRA and NICE guidance. If approved, a prescription is issued. You'll receive guidance on injection technique, storage, and when to follow up. Results vary between individuals—use our GLP-1 calculator to see potential estimates based on clinical trial data.
Ready to take control of your weight loss journey?
Start with a free BMI check, explore your GLP-1 options, or begin tracking your progress today. No sign-up. No cost. Just results.